Gossypol material balance, denaturation of protein, and loss of thiamine in commercial processing of cottonseed

Summary The processing of cottonseed by five commercial mills has been systematically examined with reference to free gossypol reduction, nitrogen solubility, thiamine reduction, material balances of total gossypol, and the distribution of gossypol in processing. One hydraulic mill reduced the free gossypol in the meal to a low level, approximating the level obtained in screw pressing. For a given mill the free gossypol contents of the meals were found to be fairly uniform. Low free gossypol content of hydraulic‐pressed meals depends on the thoroughness with which the gossypol is bound in the cooking. Gossypol is bound in both the cooking and pressing in the production of screw‐pressed meals. A relatively small amount of total gossypol is lost or destroyed in processing cottonseed by either hydraulic‐ or screw‐pressing methods. This small loss occurs while the meats are being prepared for pressing. No significant loss was found which could be attributed to the pressing operations. Serew‐pressed oils appear to contain several times as much gossypol as hydraulic‐pressed oils, with the amount dependent on the extent of the binding of gossypol in the cooking and mechanical preparation of the meats for pressing. The high temperatures developed in screw pressing contributed to a higher reduction in thiamine and nitrogen solubility than was observed for hydraulic pressing.